A method, used while building in processor memory a stack of device
objects (DOs) representing a device, there being a multi-role driver for
a plurality of roles at least one of which corresponds to the device, may
include: registering a plurality of helper drivers so as to uniquely
correspond to the plurality of roles, respectively, each helper driver
mapping uniquely to one of the multiple roles of the multi-role driver,
respectively; and indirectly specifying a corresponding one of the
multiple roles of the multi-role driver by specifying the helper driver
mapped thereto. A related apparatus and machine-readable medium bearing
machine-readable instructions may include features similar to elements of
the method.